The present invention relates to a gripper for forklifts with clamping panels adjustable in inclination.
With particular reference to the field of forklifts, as known, grippers are used which are provided with a pair of jaws movable towards and away from each other respectively to grip and release a load.
In some applications, for example when moving electrical appliances, it is necessary for the distribution of the clamping force exerted by the jaws on the load to be as uniform as possible, so as to avoid concentrations of stresses that could damage the load.
The distribution of the clamping force that the jaws apply to the load depends on the degree of parallelism of the related clamping panels that contact the opposite sides of the load itself.
This parallelism is not ensured by the fabrication tolerances and by the precision of assembly of the jaws of the grippers that, essentially, are metal construction structures.
For this reason, jaws have long been known whose clamping panels are adjustable in position—and, in particular, in inclination—in order to be able to seek and restore their parallelism, also with successive adjustments and tests, and thereby ensure a distribution of the clamping forces that is as uniform as possible also according to the load to be moved.
According to a first embodiment of the prior art shown in figures from 1 to 2A, the gripper 100 comprises a pair of jaws 101 that are mounted on a support frame 102 in a mutually movable manner, for example by sliding, between at least one close configuration for clamping the load to be moved and at least one spaced configuration for releasing the load and vice versa. The support frame 102 can be mounted on forklift. Each jaw 101 comprises a support plate-shaped body 103 that is coupled, for example through a cylindrical hinge coupling, to a mounting body 104. The mounting body 104 is in turn movably coupled to the support frame 102. The mounting body 104 is, for example, fastened to rectilinear section bars 105 slidably inserted in corresponding rectilinear guides 106 fastened to the support frame 102. The sliding motion of the two jaws 101 is achieved through respective linear actuators 107 of the type with hydraulic cylinders-pistons mounted on the support frame 102.
Each jaw 101 further comprises a respective clamping panel 108.
In this first known embodiment, the clamping panel 108 is supported by the respective support plate-shaped body 103 through a plurality of threaded connecting members.
Each threaded connecting member comprises a screw 109 that is rigidly fastened in rotation and translation to the clamping panel 108 and that is engaged in a threaded hole obtained in a corresponding bushing 110. The bushing 110 is mounted in a respective through hole obtained in the support plate-shaped body 103. The bushing 110 is inserted in the respective hole of the support plate-shaped body 103 in a freely rotating manner. A locknut 111 blocks the relative rotation of the screw 109 relative to the corresponding bushing 110. To adjust the inclination of the clamping panel 108 it is necessary to loosen the locknut 111 and, with an appropriate wrench, rotate the bushing 110 so as to impart to the screw 109 engaged therein a corresponding translatory motion with consequent localised displacement of the clamping panel 108 integral therewith.
Since the clamping panel 108 is rigidly fastened to the screws 109, it is necessary to carry out the adjustment gradually, acting individually on each of the threaded connecting members.
If it is necessary to significantly change the inclination of the panel, it is necessary to loosen the screws 109 of all threaded connecting members, so as to avoid the occurrence of localised stresses that could damage the clamping panel 108.
Moreover, between the clamping panel and the respective support plate-shaped body there remains a free space that, in some cases, can damage the load.
According to a second embodiment of the prior art shown in FIGS. 3 to 5, each jaw 201 comprises a support plate-shaped body 202 that supports a respective clamping panel 203, which is connected thereto with connecting members providing a complete rigid connection.
The rear end of the support plate-shaped body 202, i.e. the end thereof oriented towards the support frame of the gripper, is coupled through a cylindrical hinge coupling 205 to a mounting body 204. The mounting body 204 is fixed to rectilinear section bars 206 that are slidably inserted in corresponding rectilinear guides mounted on the support frame of the gripper.
The cylindrical hinge 205 consists of a pin that is fastened to the mounting body 204, extends in orthogonal direction to the plane defined by the rectilinear section bars 206 and is rotatably mounted in a corresponding seat obtained in a wing 202a of the support plate-shaped body 202.
A plurality of bolts 207 fasten in a removable manner the wing 202a, and hence the plate-shaped body 202 integral therewith, to the mounting body 204.
At the upper end of the mounting body 204 screw adjustment members 208 are provided that act on a corresponding projection of the wing 202a. 
To change the inclination of the clamping panel 203 it is necessary to loosen the bolts 207 and act on the screw adjustment members 208 so as to cause a corresponding rotation of the wing 202a, and therewith of the support plate-shaped body 202 and of the clamping panel 203 integral therewith, around the cylindrical hinge 205. Once the desired adjustment is obtained, it is necessary to tighten the locknuts 209 of the screw adjustment members 208 and the bolts 207.
The adjustment operations are, therefore, particularly laborious and long.
The structure of the jaws themselves, moreover, is particularly complex, heavy and bulky.